U.S. patent application number 14/808339 was filed with the patent office on 2016-03-10 for valve operation and diagnosis.
The applicant listed for this patent is Siemens Aktiengesellschaft. Invention is credited to Thomas Gnoss, Michael Heger, Rainer Lochschmied, Anton Pallek, Mike Schmanau, Bernd Schmiederer, Martin Wetzel, Armin Wiegand.
Application Number | 20160069772 14/808339 |
Document ID | / |
Family ID | 51539149 |
Filed Date | 2016-03-10 |
United States Patent
Application |
20160069772 |
Kind Code |
A1 |
Gnoss; Thomas ; et
al. |
March 10, 2016 |
Valve Operation And Diagnosis
Abstract
A method is disclosed for diagnosing a valve assembly having
valve members serially arranged along a flow channel of the valve
assembly connecting at least one inlet and at least one outlet of
the valve assembly. All of the serially arranged valve members of
the valve assembly are opended to allow fluid to flow through the
flow channel. The flow of fluid through the flow channel is
measured by at least one sensor. At least one of the valve members
is openend, and at least one sensor checks for fluid leakage caused
by at least one faulted valve member. The at least one sensor may
include a flow sensor, e.g., a mass flow sensor.
Inventors: |
Gnoss; Thomas; (Muggensturm,
DE) ; Heger; Michael; (Muggensturm, DE) ;
Lochschmied; Rainer; (Rheinstetten-Forchheim, DE) ;
Pallek; Anton; (Muggensturm, DE) ; Schmanau;
Mike; (Malsch, DE) ; Schmiederer; Bernd;
(Karlsruhe, DE) ; Wetzel; Martin; (Rastatt,
DE) ; Wiegand; Armin; (Lichtenau, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft |
Muenchen |
|
DE |
|
|
Family ID: |
51539149 |
Appl. No.: |
14/808339 |
Filed: |
July 24, 2015 |
Current U.S.
Class: |
700/282 ;
73/40.5R |
Current CPC
Class: |
G05D 7/0635 20130101;
F23N 2231/10 20200101; G05B 15/02 20130101; F23N 2227/20 20200101;
F23N 5/18 20130101; F23N 2227/18 20200101; F23N 5/242 20130101;
G01M 3/2876 20130101; F23N 2231/18 20200101 |
International
Class: |
G01M 3/28 20060101
G01M003/28; G05B 15/02 20060101 G05B015/02; G05D 7/06 20060101
G05D007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2014 |
EP |
14184273.2 |
Claims
1. A method of diagnosis of a valve assembly of a gas-fired
installation, which valve assembly includes a plurality of valve
members serially arranged along a flow channel of the valve
assembly connecting at least one inlet and at least one outlet of
the valve assembly, the method comprising: during an operation of
the gas-fired installation, measuring, by at least one flow sensor,
a flow of a fluid through the flow channel of the valve assembly,
closing at least one of the serially arranged valve members of the
valve assembly such that fluid flow is prevented through the flow
channel, opening at least one of the valve members of the valve
assembly to permit a fluid flow from an upstream side of the at
least one valve member to a downstream side of the at least one
valve member, measuring, by the at least one flow sensor, at least
one signal related to fluid flow, determining at least one quantity
characterizing the at least one signal, comparing the at least one
quantity to at least one threshold value, and determining that the
at least one quantity exceeds the at least one threshold value, and
in response to such determination, detecting a leakage flow having
a flow velocity between 0.1 m/s and 5 m/s caused by at least one
faulted valve member of the plurality of valve members, wherein the
at least one sensor is configured to (a) detect the leakage flow
having the flow velocity between 0.1 m/s and 5 m/s, and (b) measure
normal operational flow velocities through the flow channel of the
gas-fired installation in operation.
2. The method of claim 1, comprising closing all of the serially
arranged valve members of the valve assembly to thereby interrupt a
flow of fluid through the flow channel.
3. The method of claim 1, further comprising checking, by the at
least one sensor, for an absence of fluid flow through the valve
assembly.
4. The method of claim 1, wherein the fluid is at least one of
gaseous or combustible.
5. The method of claim 1, wherein the at least one flow sensor
comprises a mass flow sensor.
6. The method of claim 1, comprising determining at least one
quantity characterizing the at least one signal by integrating the
at least one signal.
7. The method of claim 6, comprising performing an integration of a
pulse during a time between a start point and an end point, wherein
the start point is an instant of valve opening or an instant of the
pulse reaching a first pulse threshold along a rising edge of the
pulse, and wherein the end point is a moment of the pulse reaching
a second pulse threshold along a falling edge of the pulse.
8. The method of claim 1, wherein the at least one quantity
characterizing the at least one signal is a peak of the at least
one signal.
9. The method of claim 6, wherein the at least one quantity
characterizing the at least one signal is a pulse width between a
defined point along a rising edge and a defined point along a
falling edge of the pulse.
10. The method of claim 6, comprising determining the at least one
quantity characterizing the at least one signal by multiplying the
integral and a peak of the at least one signal.
11. The method of claim 1, further comprising: comparing, by a
control unit, the at least one quantity to a quantity threshold,
and generating, by the control unit, an indication of a valve
status based on the comparison of the at least one quantity to the
quantity threshold.
12. The method of claim 11, further comprising controlling the
fluid flow depending on the valve status.
13. The method of claim 11, further comprising displaying an
indication of the valve status via a display device.
14. A non-transitory, tangible computer readable medium storing a
computer program product for diagnosing of a valve assembly of a
gas-fired installation, which valve assembly includes a plurality
of valve members serially arranged along a flow channel of the
valve assembly connecting at least one inlet and at least one
outlet of the valve assembly, the computer program product
comprising instructions executable by a processor to: during an
operation of the gas-fired installation, control at least one flow
sensor to measure a flow of a fluid through the flow channel of the
valve assembly, close at least one of the serially arranged valve
members of the valve assembly such that fluid flow is prevented
through the flow channel, open at least one of the valve members of
the valve assembly to permit a fluid flow from an upstream side of
the at least one valve member to a downstream side of the at least
one valve member, control the the at least one flow sensor to
measure at least one signal related to fluid flow, determine at
least one quantity characterizing the at least one signal, compare
the at least one quantity to at least one threshold value, and
determine that the at least one quantity exceeds the at least one
threshold value, and in response to such determination, detect a
leakage flow caused by at least one faulted valve member of the
plurality of valve members, wherein the at least one sensor is
configured to (a) detect the leakage flow having a flow velocity
between 0.1 m/s and 5 m/s, and (b) measure normal operational flow
velocities through the flow channel of the gas-fired installation
in operation.
15. A valve assembly of a gas-fired installation, the valve
assembly comprising: an inlet and an outlet, a flow channel
connecting the inlet to the outlet, a plurality of valve members
serially arranged along a flow channel of the valve assembly, at
least one actuator configured to open at least one of the valve
members, and at least one flow sensor configured to (a) detect a
leakage flow having a flow velocity between 0.1 m/s and 5 m/s,
caused by at least one faulted valve member of the plurality of
valve members and (b) measure normal operational flow velocities
through the flow channel of the gas-fired installation in
operation.
16. The valve assembly of claim 15, wherein the flow sensor is
arranged between the inlet of the valve assembly and the valve
member of the plurality of valve members that is closest to the
inlet.
17. The valve assembly of claim 15, wherein: the flow sensor is
arranged between the outlet of the valve assembly and the valve
member of the plurality of valve members that is closest to the
outlet, or the valve assembly comprises is arranged between two of
the valve members.
18. The valve assembly of claim 15, wherein at least one of the
valve members is a modulating valve member or an on/off valve.
19. The valve assembly of claim 15, wherein the valve assembly
further comprises: at least one actuator configured to actuate a
valve member, at least one control unit configured to excite the at
least one actuator using at least one excitation signal, wherein
the control unit is configured to excite the at least one actuator
in accordance with at least one predefined program sequence and in
response to at least one request signal, wherein the control unit
is configured to generate at least one indication of valve status
as a result of excitation in accordance with the at least one
program sequence, and wherein the valve assembly further comprises
at least one control gate configured to transmit or to suppress the
at least one request signal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to EP Application No.
14184273.2 filed Sep. 10, 2014, the contents of which are hereby
incorporated by reference in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to an apparatus and to a
method for testing a valve assembly. More particularly, the present
disclosure relates to an apparatus and to a method for detecting
leakage and input pressure status in a valve assembly.
BACKGROUND
[0003] Valves and valve assemblies are frequently employed in
conjunction with the regulation of the flow of a fluid. Typical
appliances are gas-fired installations, where the flow of a gas to
a combustion chamber or to a burner is regulated. Examples of
gas-fired installations include, but are not limited to, water
heaters, boilers, stoves, dryers, deep fryers, fireplaces.
[0004] Valve assemblies typically provide one or several valve
members. The valve members are arranged in a flow channel that
connects the inlet of the valve assembly to its outlet. To open or
close a gas valve, one or several actuators drive a valve member
into or out of a flow channel.
[0005] Certain applications require modulating gas valves.
Modulating gas valves allow precise control of the mass flow of a
gas by adjustment of a valve member. As the position of the valve
member of a modulated valve may be anywhere between fully open and
fully closed, the flow of a gas may vary accordingly.
[0006] A gas valve assembly may actually provide several valve
members that are sequentially arranged. With each valve member
adapted to fully close the flow channel, a solution with two valve
members achieves technical redundancy. That is, both of the valve
members need to malfunction in order for the entire assembly to
undergo failure.
[0007] Valve diagnosis may yield even more reliable solutions,
especially in cases where a (catastrophic) failure of a gas valve
is not acceptable. To that end, a gas valve may provide a plurality
of sensors and a control unit to detect leakage and/or imminent
failure.
[0008] The German patent DE102011000113B4 was granted on 14 Aug.
2013 and discloses a valve assembly 10 with two valve members 15,
16. The valve assembly according to DE102011000113B4 also provides
a pressure sensor 18. The pressure sensor 18 is configured to
measure gas pressure in a middle section 17 in between the valve
members 15, 16. Diagnostic information about the valve can be
derived from the measurement of pressure in the intermediate volume
17.
[0009] The pressure sensor 18 of the valve assembly of
DE102011000113B4 connects to a controller 11. During a diagnostic
check, the controller 11 opens or closes a first valve member 15
and then opens or closes a second valve member 16. In a subsequent
check, the controller 11 reverses the sequence of opening or
closing the valve members 15, 16. The controller will thus first
open or close the second valve member 16 and then do the same with
the first valve member 15. The reversal of the sequence aims at
extending the useful life of the assembly 10.
[0010] The patent EP1236957B1 was granted on 2 Nov. 2006 and
discloses a burner-operated device. The device comprises a valve 19
and a pressure sensor 28. Both the valve 19 and the pressure sensor
28 are connected to a control unit 30. The control unit 30 matches
a flow of combustible gas to a flow of air for optimum performance
of the burner-operated device.
[0011] The patent EP1236957B1 teaches the pressure sensor 28 may in
an alternate embodiment also be a mass flow sensor. In contrast to
a pressure sensor 28, a mass flow sensor will allow for a direct
determination of gas flow.
[0012] The aforementioned publications EP1236957B1 and
DE102011000113B4 do not focus on harnessing a flow sensor to
perform valve diagnosis. Instead, they deal either with long
service life or with optimum gas to air ratio. In particular,
EP1236957B1 and DE102011000113B4 do not teach how to come up with
diagnostic equipment that responds to rapid changes in flow rate.
Also, the disclosures of EP1236957B1 and of DE102011000113B4 do not
focus on equipment that is capable of measuring gas flow in service
and of performing valve diagnosis. That is, the combination of
accurate flow measurements and of reliable diagnosis has not been
dealt with in detail.
[0013] Start-up operations of the burner that are unnecessary to
the unavailability of combustible gas are to be avoided. The gas
input pressure is typically checked by a gas pressure sensor or by
a gas pressure switch before a fire control unit runs the start-up
sequence. In particular, a check of gas input pressure is performed
before opening both gas valves.
[0014] In addition, the input gas pressure is checked by a pressure
sensor to avoid excessive input pressure. A condition with
excessive input pressure may, for instance, occur due to a failed
pressure governor.
SUMMARY
[0015] One embodiment provides a method of diagnosis of a valve
assembly with valve members serially arranged along a flow channel
of the valve assembly, the method comprising: at least one flow
sensor measuring the flow of a fluid through the flow channel of a
gas-fired installation in operation; closing at least one of the
serially arranged valve members of the valve assembly, such that no
fluid can flow through the flow channel connecting at least one
inlet and at least one outlet of the valve assembly; opening at
least one of the valve members of the valve assembly, such that
fluid may flow from the upstream side of the at least one valve
member to its downstream side; at least one flow sensor measuring
at least one signal related to fluid flow; determining at least one
quantity characterizing the at least one signal; comparing the at
least one quantity to at least one threshold value; and checking
whether or not the at least one quantity exceeds the at least one
threshold value; wherein the at least one sensor is configured to
measure flow velocities between 0.1 m/s and 5 m/s, such that the
flow sensor is configured to measure leakage caused by an at least
one faulted valve member and is configured to measure typical flow
velocities through the flow channel of a gas-fired installation in
operation.
[0016] In a further embodiment, the method comprises the step of
closing all of the serially arranged valve members of the valve
assembly, such that the flow of fluid through the flow channel
connecting at least one inlet and at least one outlet of the valve
assembly is interrupted.
[0017] In a further embodiment, the method comprises the step of
the at least one sensor checking for the absence of flow of a fluid
through the valve assembly.
[0018] In a further embodiment, the fluid detected by the flow
sensor is gaseous and/or combustible.
[0019] In a further embodiment, the flow sensor is a mass flow
sensor.
[0020] In a further embodiment, at least one quantity
characterizing the at least one signal is determined by integrating
the at least one signal.
[0021] In a further embodiment, integration of a pulse is carried
out between a start point and an end point; wherein the start point
is selected from the instant of valve opening or from the instant
of the pulse reaching a threshold, preferably 50% of the peak of
the pulse, along the rising edge of the pulse; and wherein the end
point is the moment of the pulse reaching a threshold, preferably
10%, 50%, or 90% of the peak of the pulse, along the falling edge
of the pulse.
[0022] In a further embodiment, the at least one quantity
characterizing the at least one signal is the peak of the at least
one signal.
[0023] In a further embodiment, at least one quantity
characterizing the at least one signal is the pulse width between
the rising and the falling edge of the pulse measured at 50% or at
10% or at 90% of the peak of the pulse.
[0024] In a further embodiment, the at least one quantity
characterizing the at least one signal is determined by multiplying
the integral and the peak of the at least one signal.
[0025] In a further embodiment, the method further comprises the
step of a control unit checking the at least one quantity against a
threshold to generate an indication of valve status.
[0026] In a further embodiment, the method further comprises the
step of a control gate either enabling fluid flow, preferably
enabling fluid flow for normal steady state operation, or
permanently stopping fluid flow, or temporarily stopping fluid flow
depending on valve status.
[0027] In a further embodiment, the method further comprising the
step displaying an indication of valve status for the purposes of
maintenance, servicing and/or repair.
[0028] Another embodiment provides a non-transitory, tangible
computer readable medium having instructions executable by a
processor to perform any of the methods disclosed above.
[0029] Another embodiment provides a valve assembly, comprising: at
least one inlet and at least one outlet; a flow channel connecting
the at least one inlet to the at least one outlet; a plurality of
valve members serially arranged along a flow channel of the valve
assembly; at least one actuator for opening at least one of the
valve members of the valve assembly; and at least one flow sensor
configured to measure flow velocities between 0.1 m/s and 5 m/s,
such that the flow sensor is configured to measure leakage caused
by at least one faulted valve member and is configured to measure
typical flow velocities through the flow channel of a gas-fired
installation in operation.
[0030] In a further embodiment, the flow sensor is arranged in
between the inlet of the valve assembly and the at least one valve
member closest to the inlet.
[0031] In a further embodiment, the flow sensor is arranged in
between the outlet of the valve assembly and the last valve member
closest to the outlet or wherein the valve assembly comprises two
valve members and the flow sensor is arranged in between the two
valve members.
[0032] In a further embodiment, at least one of the valve members
is a modulating valve member or wherein at least one of the valve
members is an on/off valve.
[0033] In a further embodiment, the valve assembly additionally
comprises: at least one actuator configured to actuate a valve
member; at least one control unit configured to excite the at least
one actuator through at least one excitation signal; wherein the
control unit is configured to excite the at least one actuator in
accordance with least one predefined program sequence and in
response to at least one request signal; wherein the control unit
is configured to generate at least one indication of valve status
as a result of excitation in accordance with the at least one
program sequence; and wherein the valve assembly further comprises
at least one control gate configured to transmit or to suppress the
at least one request signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Example embodiments are discussed below with reference to
the figures, in which:
[0035] FIG. 1 shows a valve assembly according to an
embodiment.
[0036] FIG. 2 provides several graphs of a valve assembly not
leaking.
[0037] FIG. 3 provides several graphs of a valve assembly with the
downstream valve member leaking.
[0038] FIG. 4 provides several graphs of a valve assembly with the
upstream valve member leaking.
[0039] FIG. 5 is a plot of peak voltage of a mass flow sensor
versus pressure at the inlet of the valve assembly.
[0040] FIG. 6 provides several graphs with details of a measurement
while opening or closing a valve member, assuming no leakage.
[0041] FIG. 7 shows the same measurement sequence as FIG. 6, but
with the downstream valve member being faulty (leaking).
[0042] FIG. 8 shows the same measurement sequence as FIG. 6, but
with the upstream valve member being faulty (leaking).
[0043] FIG. 9 shows a leakage test that follows a normal shut down
procedure.
[0044] FIG. 10 shows another leakage test that follows a normal
shut down procedure.
DETAILED DESCRIPTION
[0045] Embodiments of the present invention provide methods and
apparatus for diagnosing a valve, e.g., a gas valve, using one or
more sensors, e.g., a mass flow sensor.
[0046] Some embodiments are based on the advent of new mass flow
sensors, e.g., new thermal mass flow sensors. These sensors allow
for measurements over a particularly wide range and very short
response times of less than 100 ms. The wide measurement range of
these mass flow sensors facilitates measurements of small flow
rates caused for example by leakages. A valve assembly with a
volume of 0.2 l may, by way of example, be configured to detect
leakages of 50 l/h. Leakages of 50 l/h typically correspond to flow
velocities between 0.01 m/s and 0.1 m/s. At the same time, the new
sensors allow for measurements of large flow rates such as flow
rates in conjunction with a gas-fired installation in operation.
Typical values of such flow rates are subsets of a range of flow
rates between 0.5 m/s and 5 m/s, 10 m/s, 15 m/s, 20 m/s, or even
100 m/s. Mass flow sensors suitable for the purposes declared
herein can be type OMRON.RTM. D6F-W or type SENSOR TECHNICS.RTM.
WBA sensors. This list is not exhaustive. The useful range of these
sensors typically starts at any of the velocities between 0.01 m/s
and 0.1 m/s and ends at any of the velocities of 5 m/s, 10 m/s, 15
m/s, 20 m/s, or even 100 m/s. That is, lower limits of 0.1 m/s can
be combined with any of the upper limits of 5 m/s, 10 m/s, 15 m/s,
20 m/s, or even 100 m/s.
[0047] Preferably, mass flow sensors suitable for the purposes
declared herein comprise a single sensor element. By contrast, mass
flow sensors with multiple sensor elements comprise two or more
sensor elements. Each of these sensor elements acts to measure flow
velocities within a limited range. An (electronic) switch may then
be employed to combine multiple sensor elements into one sensor. To
that end, the switch selects a particular sensor element in
accordance with the flow velocities to be measured.
[0048] In a further embodiment, a mass flow sensor is installed
upstream of the valve assembly.
[0049] In a further embodiment, a mass flow sensor is installed
downstream of the valve assembly.
[0050] In a further embodiment, a mass flow sensor is installed in
a flow channel between two valve members of a valve assembly.
[0051] In a further embodiment, a signal from a mass flow sensor is
integrated to provide an accurate indication of leakage.
[0052] In a further embodiment, the peak of a signal from a mass
flow sensor accurately indicates leakage.
[0053] Further embodiments provide an apparatus and a method for
valve diagnosis that harness design parameters of an installation
to enhance the quality of diagnostic indications.
[0054] Further embodiments provide an apparatus and a method for
valve diagnosis that use a time series of measurements for the
detection and/or identification of leakages.
[0055] In a further embodiment, a sensor signal is obtained after
or before opening or closing of a valve member and is processed to
derive indications of gas leakage.
[0056] In a further embodiment, a sensor signal is obtained during
opening or closing of a valve member and is processed to derive
indications of gas leakage.
[0057] Further embodiments provide a gas-fired installation with a
unit for valve diagnosis and for flow measurement.
[0058] Further embodiments provide an apparatus and a method to
generate a maintenance signal if valve diagnosis indicates a
leakage above a predefined warning threshold.
[0059] Further embodiments provide an apparatus and a method to
permanently interrupt gas flow through all valve members if valve
diagnosis indicates a leakage above a predefined lock-out
threshold.
[0060] Further embodiments provide an apparatus and a method for
input pressure diagnosis wherein a sensor signal is obtained during
opening or closing of a valve member and is processed to derive
indications of gas input pressure.
[0061] Further embodiments provide an apparatus and a method to
temporarily interrupt gas flow through all valve members if input
pressure is below a predefined minimum pressure threshold.
[0062] Further embodiments provide an apparatus and a method to
stop the gas flow through all valve members temporary while the
input pressure is over a predefined maximum pressure threshold.
[0063] Further embodiments provide an apparatus and a method to
generate a maintenance signal if input pressure drops below a
predefined minimum pressure threshold or rises above a predefined
maximum pressure threshold.
[0064] FIG. 1 shows a valve assembly with two valve members 2, 3,
according to an example embodiment. Arrow 4 indicates the direction
of fluid flow through the valve.
[0065] The valve members 2, 3 are arranged in series. In other
words, valve 3 is arranged downstream of valve 2. Accordingly, the
valve assembly provides an inlet that is arranged upstream of valve
member 2. The outlet of the valve assembly is arranged downstream
of valve member 3. A flow channel connects the inlet 2 to the
outlet 3. The valve members 2, 3 are arranged to alter the flow of
fluid through the flow channel.
[0066] The two valve members 2, 3 are each capable of interrupting
the flow of a fluid through the valve assembly provided none of
them 2, 3 is faulted. It is envisaged that at least one of the
valves 2, 3 may be a modulating valve so as to vary the flow rate
of a fluid during burner operation. A modulating valve is, however,
not required in order to provide the functionality of valve
diagnosis. A third, independent, valve may also act to vary the
flow rate of a fluid.
[0067] In a preferred embodiment the fluid flowing through the
valve assembly is gaseous at room temperature. In a particular
embodiment, the fluid is a combustible gas. In yet another
particular embodiment, the fluid is air.
[0068] A mass flow sensor 1 is arranged upstream of the first valve
member 2. The mass flow sensor 1 typically is a thermal sensor with
a wide measurement range. That is, the mass flow sensor 1 acts to
detect and to measure a small flow of fluid due to a leakage. The
mass flow sensor 1 can preferably also detect and measure large
fluxes in conjunction with a gas-fired installation in
operation.
[0069] In another embodiment, the mass flow sensor 1 is arranged in
between the two valve members 2, 3. In yet another embodiment, the
mass flow sensor 1 is arranged downstream of the two valve members
2, 3.
[0070] Each valve member 2, 3 is driven by an actuator 10, 11 with
electrical excitation. A control unit 12 drives the excitation
signals 13, 14 for each actuator 10, 11. The control unit 12
processes the sensor signal 7 of the mass flow sensor 1. The
control unit 12 may be a separate unit or it 12 can be integrated
in an existing device such as a unit for combustion control.
[0071] The control unit 12 stores a programmed sequence to apply
excitation signals 13, 14 to the valve actuators 10, 11. The
control unit 12 will send excitation signals 13, 14 and open both
valve members 2, 3 if fluid is to flow through the flow channel.
This implies a gas-fired installation in operation. The skilled
person understands that in a preferred embodiment the flow rate
through the gas assembly can be controlled by closed loop
operation.
[0072] The control unit 12 functions to provide an indication of
valve status 15. An indication of valve status 15 can actually be a
signal directed to external components. An indication of valve
status 15 may as well be directed to other software components
within an integrated system. The indication of valve status 15 acts
to show the valve status to the aforementioned parts or components.
The indication of valve status 15 also acts to transmit or to
suppress a request for operation directed to the valves whereby
both valves are open and are in steady state.
[0073] The indication of valve status 15 can be transferred via a
bus signal and/or via digitally encoded signals on wires. In
another embodiment, the indication of valve status 15 is
transferred through software installed on an integrated system
and/or through one or through several encoded analog signals. The
indication of valve status 15 may also be transferred along any
other suitable means of data transmission as understood by the
skilled person.
[0074] The indication of valve status 15 contains information about
leakage and about input pressure. The control unit 12 generates
these diagnostic data as described hereinafter.
[0075] A request signal 16 transmits a request for operation from
external parts or from software components to the control unit 12.
In case of a normal firing request, both valves will be open. In
case of no firing request, both valves will be in closed positions.
The control unit 12 may then perform one or several test sequences
to generate information about the valve status 15. If one or
several valve members 2, 3 are modulating valves with modulating
actuators 10, 11, the control unit 12 receive a request signal 16.
The control unit 12 will then transmit a modulation rate to the
actuators 10, 11 thereby setting the flow rate through the flow
channel.
[0076] Control gate 17 will transmit or suppress the input request
signal 16 in dependence on the indication of valve status 15. The
control gate 17 will suppress a request for operation 16 if valve
status 15 indicates leakage or an input pressure outside acceptable
limits. The control gate 17 can be implemented as a special
hardware and/or as software components of an integrated
microcontroller system.
[0077] FIG. 2 depicts mass flow 7a versus time 5c in the absence of
leakage. Let the two valve members 2, 3 each be closed and let the
pressure in the flow channel in between the two valves members 2, 3
be lower than the pressure upstream of valve member 2. Further, let
the mass flow sensor 1 be arranged upstream of valve member 2 as
shown on FIG. 1.
[0078] The uppermost graph of FIG. 2 shows the position 6a of valve
member 2. Valve member 2 opens the flow channel and after a while
5a valve member 2 closes again. Since the pressure in between the
two valve members 2, 3 is somewhat lower than the pressure upstream
of valve member 2, valve member 2 will experience a flow of a
fluid. Consequently, the mass flow sensor 1 will pick up a signal.
The same is indicated on the lowermost graph of FIG. 2.
[0079] There will be no flow and no indication of a flow signal 7a,
if the pressure between the valve members 2, 3 equals the pressure
upstream of the valve members.
[0080] Then valve member 3 opens and after some time 5b closes
again. The graph in the centre of FIG. 2 shows valve member 3 as it
opens and closes (6b). The upstream valve member 2 remains closed
in the meantime. The mass flow sensor 1 will not register a flow of
a fluid unless valve member 2 is leaking.
[0081] The lowermost graph of FIG. 3 shows the signal 7b picked up
by a mass flow sensor 1 with valve member 3 leaking. The uppermost
graph gives the position 6c of valve member 2 and the centre graph
gives the position 6d of valve member 3.
[0082] As the upstream valve member 2 opens, the mass flow sensor 1
will register fluid flow 7b into the middle section in between the
valve members 2 and 3. The pressure between both valves is then
below the upstream pressure, since the pressure between valves 2
and 3 drops due to leaking valve 3. The fluid flow 7b registered by
the mass flow sensor 1 will, however, not cease as the volume in
between the valve members 2 and 3 is filled with fluid. Due to the
leakage of downstream valve member 3, the fluid will keep flowing
until upstream valve member 2 closes. The leakage of valve member 3
thus yields a prolonged flow of fluid registered by mass flow
sensor 1.
[0083] FIG. 4 shows a situation similar to that of FIG. 3 except
that valve member 2 is now leaking instead of valve member 3. As
the upstream valve member 2 opens (6e), the mass flow sensor 1 may
register fluid flow 7c into the middle section in between the valve
members 2 and 3. The sensor 1 will register fluid flow 7c only if
the pressure in between the valve members 2, 3 is below the
pressure on the upstream side. The flow of fluid 7c will cease as
soon as the pressures upstream and downstream of the valve member 2
are the same. The pressures upstream of valve member 2 and in the
middle section are then equalized. The signal registered by the
mass flow sensor 1 may depend on the extent of the leakage of valve
member 2. If that leakage results in equal pressures upstream and
downstream of valve member 2 before even opening valve member 2, no
signal will be registered.
[0084] As soon as valve member 3 opens (6f), the leakage of
upstream valve member 2 will result in a fluid flow registered by
mass flow sensor 1. Valve member 2 may actually no longer obstruct
the flow channel at all. If that is the case, the valve assembly
may operate as if there was no valve member 2. The mass flow sensor
1 will then experience constant mass flow 7c versus time 5i until
closure of valve member 3.
[0085] Due to the leakage of valve member 2, the upstream mass flow
sensor 1 will record fluid flow even after closure of valve member
3. The mass flow 7c versus time 5i will actually begin to decline
as valve member 3 closes. The mass flow sensor 1 will only stop
registering a signal when the pressures upstream and downstream of
valve member 2 are equal.
[0086] FIG. 6 shows mass flow measurements carried out at the
instant of opening or of closing a valve member 2, 3. FIG. 6
details the case where no valve member shows leakage.
[0087] At the beginning downstream valve member 3 opens (6h) and
fluid flows out of the middle section between the valve members 2,
3. When the pressures upstream and downstream of valve member 3 are
equal, valve member 3 closes. Upstream valve member 2 opens
immediately thereafter (6g).
[0088] The mass flow sensor 1 then registers fluid flow in the form
of a pulse. The signal 7d registered by the mass flow sensor shows
a sharp rise as the upstream valve member 2 opens. The same signal
7d drops quickly as the middle section in between valve members 2
and 3 is filled with fluid. Valve member 2 closes upon equalization
of the two pressures in between the valves 2, 3 and at the
inlet.
[0089] After a while the upstream valve member 2 opens again (6g)
and closes a short time thereafter. This time the mass flow sensor
1 will not record a signal, because the pressures upstream and
downstream of valve member 2 should be the same.
[0090] Graph 6h shows that downstream valve member 3 then opens and
closes. By opening and closing valve member 3, the middle section
will be vented towards the outlet of the valve assembly. Since the
mass flow sensor 1 is arranged upstream of valve member 2 and valve
member 2 is closed, the sensor 1 will not pick up a signal.
[0091] The sensor 1 will, however, pick up a signal as soon as
valve member 2 opens. Fluid from the inlet of the valve assembly
then enters the middle section in between valve members 2 and 3.
The mass flow sensor 1 will pick this up in the form of the short
pulse shown on graph 7d.
[0092] It is envisaged that the integrals of the pulses shown on
graph 7d are employed to further analyze leakage. In an alternate
embodiment, the peaks of the same pulses are used to further
process the signals obtained.
[0093] In yet another embodiment, integration of a pulse is carried
out between a start point and an end point. The start point may be
the instant when the valve opens. Alternatively, the start point is
defined as the instant when a given threshold along the rising edge
of a pulse is reached. The end point is defined as the instant when
a given threshold, preferably 50% of the peak of the pulse, along
the falling edge is reached. In an alternate embodiment, the
definition of the end point relies on another percentage such as
90% or 10% of the peak of the pulse. The quantities derived in this
manner provide fair estimates of pulse magnitudes.
[0094] In yet another embodiment, the magnitude of a pulse is
determined by multiplying the peak of a pulse with its width. Pulse
width is, for instance, measured between 50% of the peak of the
pulse along the rising and falling edges. In yet another
embodiment, the magnitude of a pulse is determined by multiplying
the peak of a pulse with its integral.
[0095] It is envisaged that the integration of a pulse obtained
from the mass flow sensor 1 is triggered as at least one of the
valve members 2, 3 commences its open operation.
[0096] In yet another embodiment, quasi-integration is employed to
analyze the pulses obtained from the mass flow sensor 1.
Quasi-integration relies on a low-pass filter. The bandwidth of
this filter is chosen such that its upper limit is shorter than the
inverse of the duration of a typical pulse. Typical pulses last
between 100 milliseconds and 300 milliseconds and most pulses are
shorter than 500 milliseconds. In a particular embodiment, the
upper limit of the bandwidth of the quasi-integration filter is at
least three times lower than the inverse of pulse duration.
[0097] The previous steps of pulse analysis can, for instance, be
carried out by a microprocessor receiving data from the mass flow
sensor 1. In a preferred embodiment, the microprocessor is
integrated in the control unit 12. It is also envisaged that the
microprocessor provides memory for storing time series of
pulses.
[0098] Once a quantity has been derived that corresponds to the
magnitude of the pulse, the same quantity may be compared to a
threshold value. The threshold value may be a historical threshold
value stored in the memory of the microprocessor. The threshold
value may also rely on design parameters of the valve assembly such
as typical close/open times of valve members, the volume of the
middle section etc. Further, an operator may set and/or change
threshold values.
[0099] It is envisaged that the valve assembly, in particular its
microprocessor, is configured to output a warning signal when the
magnitude of a pulse exceeds a first threshold. It is also
envisaged that the valve assembly will output a lock-out signal
when the magnitude of a pulse exceeds a second threshold. The
warning signal and the lock-out signal are typically part of the
indication of valve status. Also, a timestamp may be determined and
attributed to a signal such as a pulse. It is envisaged that the
microprocessor factors in the timestamp of a signal (such as a
pulse) prior to outputting a (lock-out or warning) signal.
[0100] It is further envisaged that comparison of pulse magnitude
with threshold values is carried out by analogous circuits within
the control unit 12. Analogous circuits known in the art comprise
potentiometers to set threshold values. Analogous circuits for
pulse comparison may also provide Schmitt-trigger elements based on
operational amplifiers.
[0101] The peak of the signal obtained from the mass flow sensor 1
can be employed to determine the pressure at the inlet of the valve
assembly. To that end, FIG. 5 shows a plot of peak signal 9
measured by the mass flow sensor 1 versus pressure 8 at the inlet
of the valve assembly.
[0102] The peak value or any other meaningful magnitude of the
pulse obtained from the sensor 1 yields the amount of fluid flowing
into the middle section. The volume of the middle section in
between valve members 2 and 3 and/or a previously obtained
reference value can be used to derive the pressure 8 at the inlet
of the valve assembly.
[0103] A situation similar to that of FIG. 6 is depicted on FIG. 7.
The only difference between FIG. 6 and FIG. 7 is that the
downstream valve member 3 is now assumed to be leaking.
[0104] FIG. 7 shows the same sequences 6i, 6j of valve members 2,
3, opening and closing as FIG. 6. At the beginning, valve member 3
opens and closes and this is followed by valve member 2 opening and
closing. As is the case on FIG. 6, the mass flow sensor 1 picks up
a signal when the upstream valve member 2 opens (6i).
[0105] After some time, the upstream valve member 2 opens again.
Since valve member 3 is now assumed to be leaking, a pressure loss
will have occurred in the middle section between valve members 2
and 3. By opening the upstream valve member 2, the pressures
upstream and downstream of this valve member 2 are equalized. The
mass flow sensor 1 will consequently pick up a signal 7e. This
signal corresponds to the pressure loss in the middle section
induced by leaking valve member 3.
[0106] In other words, the presence of a leak in valve member 3 is
identified by the presence of an additional pulse obtained from the
mass flow sensor 1. The magnitude of the leak can, by way of
example, be derived from the integral, from the peak height or from
the quasi-integral of that pulse. The valve assembly may continue
and process the signal as outlined in the above notes on signal
processing.
[0107] A situation similar to that of FIGS. 6 and 7 is depicted on
FIG. 8. The only difference is that the upstream valve member 2 is
now leaking.
[0108] FIG. 8 shows the same sequences of valve members 2, 3
opening and closing as FIGS. 6 and 7. At the beginning, valve
member 3 opens and closes (6l) and this is followed by valve member
2 opening and closing (6k). As is the case on FIGS. 6 and 7, the
mass flow sensor 1 picks up a signal when the upstream valve member
2 opens.
[0109] FIG. 8 shows that some time is allowed to lapse in between
the closing of valve member 3 and the opening of valve member 2.
The time span between subsequent operations of valve members
typically is 3 seconds to 20 seconds, preferably 3 seconds to 12
seconds, yet more preferably 3 seconds to 5 seconds.
[0110] The upstream valve member 2 is now assumed to be leaking.
Consequently, some fluid will leak into the middle section of the
valve assembly between the closure of valve member 3 and the
opening of valve member 2. When valve member 2 opens again, the
middle section in between the two valve members 2, 3 will be filled
with fluid to some extent. The amount of fluid passing valve member
2 and entering the middle section will be less than in case of no
leakage. Consequently, the final peak in the plot of mass flow
sensor signal 7f versus time 5r is now smaller than it is on FIG.
6.
[0111] In other words, in the present scheme a leakage of upstream
valve member 2 is detected by means of a final pulse with reduced
magnitude. The magnitude of the leak can, by way of example, be
derived from the integral, from the peak height or from the
quasi-integral of that pulse. The valve assembly may continue and
process the signal as outlined in the notes on FIG. 6.
[0112] FIG. 9 shows a valve leakage test that is carried out after
a shut down procedure. It seems worth stressing that FIGS. 9 and 10
assume no leakage.
[0113] As the valve assembly shuts down fluid flow, valve member 2
closes first. Subsequently, valve member 3 closes. The same is
indicated in the upper two graphs 6m, 6n of FIG. 9. Graph 7g shows
that fluid flow is interrupted as soon as the upstream valve member
2 closes. Now the same pressures apply to the middle section in
between the two valve members 2, 3 and the outlet of the valve
assembly.
[0114] After a while valve member 2 opens and closes again. Fluid
enters the middle section and the mass flow sensor 1 registers a
pulse. If the upstream valve member 2 was leaking, the magnitude of
that pulse would be reduced. The reduction in pulse magnitude
actually depends on the extent of the leakage.
[0115] A period of time is allowed to lapse and valve member 2
opens and closes again. The mass flow sensor 1 should not pick up a
pulse unless downstream valve member 3 is faulted and shows
leakage.
[0116] After the start-up sequence of the fire installation has
begun, then valve member 3 opens and closes. The middle section of
the valve assembly will then be vented towards the outlet of the
assembly. A mass flow sensor arranged upstream of valve member 2
will still not record a pulse, because valve member 2 remains
closed.
[0117] Soon thereafter, valve member 2 opens. The mass flow sensor
1 now registers a pulse. The same pulse will fade quickly, because
downstream valve member 3 is still closed. By using this pulse in
the manner described above the input pressure of fuel is measured.
The measured value is then checked. If input pressure is within
predefined limits, the start-up sequence of the burner start-up
will continue. If this value is outside predefined limits, the
input pressure will either be too high or too low. Both of the
valve members 2, 3 will shut and the valve status 15 will indicate
a stop of the fire installation.
[0118] As valve member 3 opens, both valve members are in their
open positions. The mass flow sensor 1 will now indicate stationary
fluid flow through the valve assembly.
[0119] The present disclosure is not limited to mass flow sensors
being arranged upstream of valve member 2. FIG. 10 shows a sequence
of valve operations with a mass flow sensor arranged downstream of
valve member 3.
[0120] At the beginning the valve assembly shuts off fluid supply
by first closing valve member 3 and then closing valve member 2
(6p, 6o). It seems worth noting that the order of closing and
opening valve members in FIG. 10 is reversed compared to FIG. 9.
The signal registered by the mass flow sensor is shown on FIG. 7h.
The downstream sensor detects a signal until the first of the two
valve members 2, 3 closes.
[0121] After a defined period of time valve member 3 opens and
closes. The mass flow sensor picks up a signal as the middle
section is vented. If valve member 3 was faulted and leaking, the
peak registered by the mass flow sensor would be lower than the
peak shown on FIG. 10.
[0122] After a while valve member 3 opens and closes again. The
mass flow sensor no longer picks up a signal, since the middle
section has been vented before. If valve member 2 was leaking, that
leakage would result in an extra amount of fluid in the middle
section. The same amount would be registered by the mass flow
sensor.
[0123] After commencement of the start-up sequence of the firing
control unit, the upstream valve member 2 will open and close. This
operation has no effect on the mass flow sensor, since the sensor
is now assumed to be arranged downstream.
[0124] The mass flow sensor only registers a short pulse as valve
member 3 opens. By using this pulse in the manner described above
the fuel input pressure is measured. The measured pressure value is
checked. If it is within predefined limits, the burner will
continue to operate. As the valve member 2 opens, the middle
section of the valve assembly gets filled with gas. The mass flow
sensor finally records stationary flow as soon as the two valve
members 2, 3 are in their open positions. It seems worth stressing
that FIGS. 9 and 10 give examples of how the same mass flow sensor
is used to record stationary flow and to detect leakage. The mass
flow sensor will record stationary flow when the two valve members
2, 3 are open. This is typically the case while a gas-fired
installation is running. The same mass flow sensor also registers
peaks when the middle section of the assembly is vented or refilled
with fluid. The same is typically the case during leakage
tests.
[0125] As described above, a defined quantity is determined as a
result of each test. A control unit 12 compares this quantity to a
predefined threshold. The predefined threshold for leakage tests of
valve member 2 may actually be different from the predefined
threshold for leakage tests of valve member 3. Also, the thresholds
for minimum or for maximum gas pressures usually differ from
thresholds for leakage tests.
[0126] The aforementioned thresholds are provided to control unit
12 by data transfer from external physical parts or from software
components. Thresholds may actually be directly programmed into the
control unit 12.
[0127] By using at least one test result, preferably by using a
plurality of test results, the control unit 12 analyses the results
of the abovementioned diagnostic test sequences. The control unit
12 eventually generates an indication of valve status 15.
[0128] Possible indications of valve status are "status correct"
and/or "OK" and/or "small leakage" and/or "critical leakage" and/or
"input pressure too low" and/or "input pressure too high". This
list is not exhaustive. Also, some of these indications may be
omitted. It is envisaged that in indication of valve status 15 does
not contain information about input pressure. It is also envisaged
that no indication of "small leakage" is generated or
transmitted.
[0129] The indication of valve status 15 should allow other
external software components or physical components to process
and/or to display the valve status. An indication of valve status
15 also functions to suppress a request signal 16 if required.
[0130] In an exemplary embodiment indications of valve status 15
are processed as follows: [0131] "status correct", "OK": Normal
valve operation for gas firing possible on request. Control gate 17
enables request of signal 16. No display of a special warning
signal for maintenance. [0132] "small leakage": Normal valve
operation for gas firing possible on request. Control gate 17
enables request of signal 16. Display of a special warning signal
for maintenance. [0133] "critical leakage": Stop of operation for
gas firing. Control gate 17 disables request of signal 16. Display
of a special lock-out signal. Request signal 16 with no effect. Gas
firing not possible. [0134] "input pressure too low": Stop of
normal valve operation until the valve diagnosis control unit 12
changes valve status 15. Control gate 17 disables a request of
signal 16 during this time. [0135] "input pressure too high": Stop
of normal valve operation until the valve diagnosis control unit 12
changes valve status 15. Control gate 17 disables a request of
signal 16 during this time.
[0136] The states "small leakage" or "critical leakage" can be sub
classified as applying to valve member 2 or to valve member 3. This
approach allows assignment of maintenance and of failure signals to
individual valve members 2, 3.
[0137] The measured value of gas input pressure can be transmitted
by the control unit 12 to other external components. These external
components may process and/or may display pressure. An installation
routine may, for instance, use the transmitted pressure value and
adjust a pressure governor mounted upstream of the valve. The
pressure value may as well become a set point of an automatically
adjustable pressure governor. In another embodiment, the control
unit 12 transmits leakage values of one or of all gas valves in
order to display a leakage status for maintenance purposes.
Transmission of input pressure values and of leakage values is
generally part of the transmission of the indication of valve
status.
[0138] The skilled person understands that in a preferred
embodiment the flow sensor is directly mounted in the flow channel.
The skilled person also understands that the flow sensor can
alternatively be mounted in a branch of the flow channel.
[0139] Any steps of a method according to the present disclosure
may be embodied in hardware, in a software module executed by a
processor, or in a cloud computer, or in a combination of these.
The software may include a firmware, a hardware driver run in the
operating system, or an application program. Thus, embodiments of
the invention also relate to a computer program product for
performing the operations presented herein. If implemented in
software, the functions described may be stored as one or more
instructions on a computer-readable medium. Some examples of
storage media that may be used include random access memory (RAM),
read only memory (ROM), flash memory, EPROM memory, EEPROM memory,
registers, a hard disk, a removable disk, other optical disks, or
any available media that can be accessed by a computer or any other
IT equipment and appliance.
[0140] It should be understood that the foregoing relates only to
certain embodiments of the invention and that numerous changes may
be made therein without departing from the spirit and the scope of
the invention as defined by the following claims. It should also be
understood that the invention is not restricted to the illustrated
embodiments and that various modifications can be made within the
scope of the following claims.
REFERENCE NUMERALS
[0141] 1 mass flow sensor 2 upstream valve member 3 downstream
valve member 4 direction of flow 5a-5x time 6a-6p valve positions
7a-7h signal obtained from the mass flow sensor 8 pressure at the
inlet of the valve assembly 9 peak voltage measured by the mass
flow sensor 10, 11 valve actuators 12 control unit 13, 14
excitation signals 15 indication of valve status 16 input signals
17 control gate
* * * * *